1. Field of the Invention
The present invention relates to a seat belt system having a plurality of buckle apparatus.
2. Description of the Related Art
An ordinary seat belt system is constructed so that a seat occupant, after being seated on a seat, brings a tongue plate on an end of a restraining webbing into engagement with a buckle body so that the seat occupant is restrained to the seat.
When using a seat belt system having a plurality of buckle apparatus, a tongue plate on a restraining webbing for a seat occupant may be brought into engagement with the buckle body of another buckle apparatus intended for another seat occupant. Erroneous fitting of a tongue plate in a wrong buckle body therefore tends to occur in seat belt systems having a plurality of buckle apparatus.
In order to overcome this problem, Japanese Utility Model Application No. 60-170590 discloses a seat belt system having a plurality of seat belt units, wherein the tongue plates of different buckle apparatuses are provided with projections at different positions while mating recesses are formed in buckle bodies of different buckle apparatuses such that each tongue plate can engage only with the buckle body of the same buckle apparatus.
The above-described known seat belt system, however, suffers from a problem in that the appearance of the seat belt system is impaired due to the irregularlity of appearances of the tongue plates and buckle bodies. In addition, the use of different shapes of tongue plates and buckle bodies makes it difficult to standardize the design of parts or common use of the parts by different buckle apparatuses.